1. Field of the Invention
The invention is a self-regulated Electrothermal Flow (ETF) micropump for infusion of fluids into the body of a patient. The self-regulated ETF micropump can also be used other application requiring miniaturized, self-regulating pumps. The micropump monitors flow rates using Laser-Induced Fluorescence Photobleaching Anemometry (LIFPA), impedance anemometry, or other flow measuring device. Data from fluid monitoring is transferred to a control system that controls the flow rate generated by the pump. The operation of the micropump can be set to maintain a constant flow rate or to deliver a pre-programmed flow rate pattern, for example.
2. Description of Related Art
Infusion pumps have a wide range of applications such as the controlled delivery of antibiotics, antiviral agents, anesthesia, chemotherapy, total parenteral nutrition (TPN), and patient-controlled analgesia. Control of infusion rates is particularly important for delivering small volumes of high concentration drugs and high flow rate infusions of large volumes.
Miniaturized, self-regulated flow pumps for drug infusion allow, for example, the controlled delivery of concentrated drug over extended periods to ambulatory patients (low flow rate) and the controlled infusion of high volumes of fluids (high flow rate).
Miniaturized electrokinetic pumps to move fluids through microfluidic devices are known and employ a variety of elecrtokinetic phenomena including electroosmotic flow, and electrohydrodynamic flow.
The use of time varying waveform ETF, such as traveling-wave ETF in applications such as micropumps is disclosed in U.S. Pat. No. 7,189,578, which is incorporated by reference in its entirety. Unlike other electrokinetic phenomena, the ETF generated by the present invention provides mean pumping velocities that increase with the 4th power of the applied voltage. This enables ETF pumps to generate higher flow rates and hence, head pressures than existing electrokinetic pumps. A theoretical description of ETF is described in Ivan R et al. (2004) J. Phys. D: Appl. Phys. 37:2323-2330, which is incorporated by reference in its entirety.
In addition to providing high flow rates and/or head pressures through the use of ETF, the present invention provides for a self-regulating micropump that monitors the pump's flow rate. This is accomplished by coupling a flow rate monitor or sensor with a pump power supply controller. The self-regulated micropump and controller may be located outside or inside the body of a patient. The flow rate produced by the pump is measured using, for example, Laser-Induced Fluorescence Photobleaching Anemometry (LIFPA) or Flow Induced Differential Electrochemical Impedance Spectroscopy (FI-DEIS).